Totally agree we don't have enough information on this one. But here's what I think, based on what we do know...
I think she probably did jaywalk. I accept that she was grabbed ("gently") by one of the cops. So far, so good. I believe she was unaware of her surroundings because of the headphones, and reacted in what the cop(s) chose to interpret as an aggressive manner. At that point, I believe that EVERYBODY overreacted, starting with the police... though she didn't really help her own cause, either.
She might very well be a drama queen, hence the screaming. I'm not so sure she intentionally screamed as a way to get the attention of others, as if it were part of a quickly thought out plan, but I do think it will end up serving her well as now the incident is in the light of day and the police cannot sweep it under the rug and pretend that everything on their end was just peachy, as they are usually wont to do.
Now, *I* never walk in public with headphones, precisely because I don't want to be unaware of my surroundings, but many people do. To be fair, it is entirely possible that her first thought when grabbed was that it was a mugger, or worse. If so, her reaction would have been entirely appropriate and justified. And a cop should be aware enough of this possibility to have it in his mind when he grabs her. All he needed to do once he had her attention was say, "Hey, It's just me. Nobody's here to do you harm, but we need to talk about that jaywalking you just did." It would have diffused the situation with no harm, no foul.
Unfortunately, it seems we're not interested in diffusing situations anymore.